People and vehicles stranded in floodwaters, inundated business premises, interrupted connectivity, and access to other services cut off. Does this need to be the new normal in the era of climate change in Indonesia’s growing cities? We don’t think so. New approaches can be employed to address flood risks through risk-informed urban design and innovative measures.
Over the past 20 years floods have impacted more people in Indonesia than any other type of natural disaster, causing significant damage and disrupting local and regional economies. In 2019 alone, floods in South Sulawesi, Papua, and Bengkulu caused over 220 deaths, with damage and losses estimated at $128 million.
The poor and vulnerable bear the brunt of floods, often because they live in vulnerable areas and have limited assets to recover from flood events. In addition, poor‑quality infrastructure is often constructed in flood‑prone areas, with inadequate consideration of risk‑informed planning and building codes.
Cities are particularly vulnerable to floods due to their high concentration of people and assets, as well as proximity to rivers and coasts. Heavy rains during the monsoon season, rising sea levels, accelerated levels of unregulated urban development, land-use changes and deforestation, and land subsidence, all contribute to increasing urban flood risk. Between 2006 and 2017 the number of reported flood events in 92 Indonesian cities tripled; from 50 to 146.
A recent World Bank (WB) analysis estimates that by 2055, the number of Indonesians exposed to river flood risk will increase by 75 per cent when compared with 2015.
Innovative flood management methods
Cities have traditionally relied on public investments in engineered ‘grey’ flood protection measures, such as dykes, pumping stations, and weirs, but the contemporary impacts of urbanisation and climate change calls for new and innovative approaches. These include:
- Nature-based and green solutions: Promoted by many cities globally, these approaches regard water (storm water, groundwater, and wastewater) as a resource that can be retained on a site, public space, or open space, for re-use or filtration.
They help reduce the stress placed on a city’s drainage during intensive rainfalls and can have co‑benefits related to maintaining sustainable waterways and improving urban amenity.
Common strategies can include permeable pavements, rain gardens, rainwater catchment tanks, detention ponds/basins, wetlands, swales, multi‑purpose reservoirs, and other green infrastructure solutions.
- Dedicated funding mechanisms (e.g., Singapore’s ABC Waters Programme – see below – and China’s Sponge Cities Program) finance priority investments in urban flood resilience, complemented by innovative funding options such as green bonds and land value capture.
Financing ongoing operations and maintenance costs at the local level can be done through earmarking local services fees for flood risk mitigation and private sector participation.
- A balanced integration of structural measures such as dredging, channeling works, pumping stations, sluice gates, drainage systems, small-scale community-based works, and nature-based and green solutions; and nonstructural measures such as risk-informed land use planning, building guidelines, hazard mapping, hazard monitoring, forecasting, early warning systems, disaster risk financing, community awareness and education, and capacity building.
The World Bank is already supporting such integrated projects in countries such as Lao PDR and the Philippines.
- Use of design “charrettes” or mini studios with stakeholders (including government, non-government/community organisations, and private citizens) that encourage participants to work on design options based on pre‑determined parameters—such as flood hazard maps, stormwater runoff calculations—and broad visions to create places that are liveable, inclusive, and sustainable.
Following design charrettes at the 2nd Technical Deep Dive on Integrated Urban Flood Risk Management in Tokyo, a similar exercise was carried out with Indonesian government officials to develop localised and integrated urban flood resilience interventions on a selected urban site.
In July 2019, the Ministry of National Development Planning (Bappenas) convened a workshop, inviting central and local government officials from five cities (Ambon, Bima, Manado, Padang and Pontianak) to discuss the proposed national urban flood resilience programme.
Facilitated by the World Bank East Asia Pacific Disaster Risk Management (DRM) team and Tokyo DRM Hub, a “design charrette” allowed participants to explore ways to incorporate nature-based and green solutions to reduce stormwater runoff.
Already being implemented
These included storm water harvesting solutions, constructed wetlands, green roofs, increasing the amount of permeable and infiltration surfaces, and incorporating recreational features (such as tiered seating and water “play” areas). Such solutions are already being implemented in cities such as Semarang, Medan and Pontianak.
The government of Indonesia and the World Bank, with financial support from the Global Facility for Disaster Reduction and Recovery and the Indonesia Sustainable Urbanization Multi-Donor Trust Fund, will be working together to establish a national urban flood resilience programme in line with the above considerations.
The programme will support select cities to strengthen their flood resilience holistically, integrating innovative nature-based and green solutions together with traditional grey infrastructure measures, and promoting gender-inclusive and disability-inclusive development.
An urban design approach to flood resilience is expected to result in many positive co-benefits across growing Indonesian cities. Indeed, living in greener, inclusive and more resilient cities will become the “new normal” for Indonesians in the future.
This article was written by Jian Vun, Jolanta Kryspin-Watson, and Kevin Simulya Alyono It first appeared on World Bank Blogs under a Creative Commons License and is reproduced here with its permission.
Feature video World Bank
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- Flood sweeps away final year varsity student in Ondo (The Nation)
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